Figure 5.

ORAI1 distributions in activated cells display a variety of two-dimensional structures. (A) The original STEM image (with QD labels outlined in yellow) gives an impression of the regional cellular morphology, with thicker cellular areas appearing brighter than thinner ones. A bulging membrane topography often matches with dense accumulations of ORAI1. Typical ellipsoid puncta (outlined with dashed lines) and nearby running several micrometer-long strands of aligned ORAI1 (transparent red traces) can be seen. (B,C) show other processed STEM images from cells with a relatively lower (B) and higher (C) ORAI1 expression level, displaying all detected labeled ORAI1, including monodisperse and dimeric label conformations, as 35 nm diameter circles. In (B), micrometer-long chains of ORAI1 formations emerge, several of them running in parallel. In (C), ellipsoid ring-like structures of ORAI1 distributions of different dimensions are visible, with the larger of these structures enclosing a central region of condensed ORAI1. Scale bars = 1 μm.